1. Field of the Invention
This invention relates generally to the field of engine muffling systems. More particularly, the invention relates to a muffler having a tortuous path through multiple chambers including a plenum chamber that operates as a Helmholtz tuning chamber.
2. Description of the Prior Art
Mufflers are employed in engine exhaust systems to limit the pressure levels of exhaust noise and to reduce sound levels of exhaust gasses emitted from an engine. Mufflers generally are classified as either reactive or dissipative.
Reactive mufflers generally include a number of resonating chambers of different volumes and shapes connected together with pipes. Reactive mufflers may include flow-reversals or baffles. Such configurations however, produce a relatively high pressure drop, causing a back pressure at the exhaust of the engine, thus limiting engine performance.
Dissipative mufflers generally include ducts or chambers which are filled with acoustic absorbing materials such as fiberglass, steel wool, porous ceramic, and the like. These acoustic absorbing materials absorb the acoustic energy and transform it into thermal energy. Sound absorbing materials generally employed in dissipative mufflers tends to deteriorate because of the structure of the material and the high velocity and temperature of the exhaust.
Sounds or noises associated with engine exhausts are known to be reduced by passage of the exhaust gasses through a plurality of small holes of an elimination chamber so that the gasses react to lower their sound level(s). Expansion chambers are often employed in mufflers by introducing the exhaust gasses into a chamber where they are expanded and then emitted or passed along to further muffler chambers.
While mufflers including a combination of some of the above structures are known in the art in a variety of configurations, such known muffler structures are generally disadvantageous in that they are not compact when employed in vertical exhaust applications. Further, conventional muffler structures, although useful in reducing sounds of exhaust gasses from an engine, are incapable of self-tuning to meet the needs of multiple applications.
In view of the foregoing, it would be advantageous and beneficial to provide a muffler having a single compact structure suitable for providing engine exhaust sound reduction for a plurality of applications, particularly vertical exhaust applications.